Damper and vehicle seat

ABSTRACT

A damper is provided which damps an applied external force in accordance with the strength of the external force (impact strength). The damper  10  comprises a vessel  20  having a cylindrical chamber  21  filled with a viscous fluid, a turn member  60  turned by the external force, a slider member  40  which is moved in the chamber  21  of the vessel  20  by turn of the turn member  60,  partition member  80  engaged with the slider member  40,  a coiled spring  100  for energizing the slider member  40  toward the turn member  60,  and a resin cap  100  blocking an opening of the vessel  20.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.12/444,534, filed Apr. 6, 2009.

TECHNICAL FIELD

The present invention relates to a damper for reducing an impact orattenuating a vibration or movement, relating for example to a dampersuitable for damping movement of a turning body, and a vehicle seatincorporating this damper.

BACKGROUND TECHNIQUE

Dampers (shock absorbers or vibration attenuators) are widely used inmachines and apparatuses to reduce an impact or attenuate a vibration ora movement. Generally, the damper utilizes elasticity or viscosity of arubber, a spring, air, or oil contained in the damper for absorbing thekinetic energy of the impact. For strengthening the power for kineticenergy absorption (damping power), usually the rubber contained isincreased or the spring contained is made larger. Therefore the powerfuldamper is necessarily larger in size.

In vehicles, a headrest is installed on the vehicle seat to protect asitting person from an accidental impact. The headrest is designed tomove forward on a rear end collision to protect the head of the sittingperson. (See for example Patent Documents 1 and 2.) Such a constitutionis complicated and costly.

(Patent Document 1) Japanese Patent Application Laid-Open No.Hei-10-181403(Patent Document 2) Japanese Patent Application Laid-Open No.Hei-10-006919

DISCLOSURE OF INVENTION Problem to Be Solved by the Invention

The installation of the above-mentioned damper on a vehicle seat isconsidered which is movable forward by an action of an impact from thevehicle rear side.

In the constitution in which the above damper is incorporated into avehicle seat to be movable forward by action of an impact, the headrestcan be moved forward by a slight external force such as hand-pushingforce applied to the vehicle seat. That is, even a slight impact otherthan the accidental impact can move the headrest forward. On the otherhand, in the constitution in which the headrest will not be moved by aweak external force like hand-pushing, the headrest may not be moved byan accidental impact.

In view of the above matters, the present invention intends to provide adamper having a damping force variable in correspondence with thestrength of an external force (impact strength) applied, and to providea vehicle seat incorporating the damper.

Means for Solving Problem

For achieving the above object, the damper of the present invention fordamping an external force comprises:

(1) a vessel having a cylindrical chamber therein;(2) a slider member placed in the chamber and dividing the chamber intotwo small rooms and movable in the cylindrical chamber;(3) a turn member placed in one of the two small rooms, turned by theexternal force, and converting the turning force into a driving force ofthe slider member;(4) a viscous fluid filled in the chamber;(5) a partition member engaged with the slider member and having acommunication path for flow of the viscous fluid between the two smallrooms;(6) a coiled spring for energizing the slider member toward the turnmember; and(7) a cap fixed to the vessel by engaging with the slider member andblocking an opening at one end of the vessel.(8) The partition member may have an orifice as the communication path.(9) The slider member may have a cylindrical boss having at the end facethereof a groove serving as the communication path.(10) The turn member may have a circular cylindrical slope portionhaving slope faces.(11) The slider member may have a circular cylindrical slope portionhaving slope faces for engaging with the slope faces of the turn member.(12) The slider member may be constituted to move in the cylindricalchamber by turning the turn member engaging the slope faces of the turnmember with the slope faces of the slider member.(13) The slider member may have plural curved plates rising along theperimeter at even intervals on the face confronting the cap; and(14) the cap may have plural curved plates rising along the perimeter ateven intervals on one of the face thereof; and(15) the curved plates of the slider member may be inserted into theintervals of the curved plates of the cap to engage the slider memberwith the cap at the periphery direction.

The vehicle seat of the present invention, for achieving the aboveobject, which has a headrest placed at the top of a backrest to be incontact with the back of a riding person for protecting a head of theriding person, and an energizing mechanism for energizing the headrestto move toward the front side of the vehicle, and a stopping mechanismto stop the energizing of the energizing mechanism not to cause movementof the headrest toward the front side of the vehicle, comprises:

(16) the damper set forth in any of the above items (1) to (15), placedin the backrest;(17) in the damper, when the turn member is turned by an external forceapplied to the turn member at a turning rate less than a predeterminedrate, the slider member is moved in the cylindrical room of a vessel byturn of the turn member, and the external force is attenuated bythrottle resistance caused by the flow of the viscous fluid through thecommunication path; and when the turn member is turned by an externalforce applied to the turn member at a turning rate more than thepredetermined rate, the turn member and the slider member arerigid-coupled and the slider member and the cap are turned together withthe vessel; and comprises further(18) an external force receiving pad which is placed inside the backrestand turns the turn member of the damper on receiving the external forcegiven to the backrest; and(19) a releasing mechanism which releases the stopping of the stoppingmechanism to start the energizing mechanism in accordance with the turnof the vessel and the cap fixed to the vessel.(20) The releasing mechanism may work only when the turn member of thedamper is turned at a turning rate higher than a predetermined rate.

Effect of Invention

The damper of the present invention is capable of damping an externalforce by utilizing a throttle resistance of a viscous fluid at acommunication channel when a turn member is turned by an external force(turning force) applied to the turn member at a turning rate less than apredetermined rate. When this damper is turned by an external force(turning force) applied to the turn member at a turning rate more than apredetermined rate, the throttle resistance of the viscous fluid at thecommunication path becomes extremely higher to cause rigid couplingbetween the turn member and a slider member. Thereby the slider memberis turned together with the cap and the vessel. The vehicle seatincorporating this damper is capable of distinguishing precisely arear-end collision impact from other external forces. Therefore only atthe rear end collision, a stopping mechanism is released to turn the capof the damper and to activate the energizing mechanism to move theheadrest surely forward.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a damper. FIG. 1B is an exploded viewof the damper in FIG. 1A, illustrating the constituting members.

FIG. 2A is a side view of the slider member. FIG. 2B is a developmentview of the slope portion of the slider member.

FIG. 3A is a side view of the turn member. FIG. 3B is a development viewof the slope portion of the turn member.

FIG. 4 is a simplified sectional view of the damper which is notaffected by an external force.

FIG. 5 is a simplified sectional view of the damper in which the slidermember is displaced maximally by an external force.

FIG. 6 is a sectional view illustrating the movement in the damper onreleasing the external force.

FIG. 7A is a sectional view of the partition member which is notdeformed elastically. FIG. 7B is a sectional view of the partitionmember which is deformed elastically.

FIG. 8 is a schematic side view of a vehicle seat incorporating thedamper illustrated in FIG. 1 and other drawings.

FIG. 9 is a front view of the vehicle seat illustrated in FIG. 9.

BEST MODE FOR CARRYING OUT THE INVENTION

Examples of carrying out the present invention are described below indetail with reference to drawings without limiting the present inventionin any way.

EXAMPLES

An example of the damper of the present invention is described withreference to FIGS. 1-3.

FIG. 1A is a schematic perspective view of an example of the damper.FIG. 1B is an exploded view of the damper of FIG. 1A, illustrating theconstituting members. FIG. 2A is a side view of a slider member; FIG. 2Bis a development view of the circular cylindrical slope portion of theslider member. FIG. 3A is a side view of the turn member. FIG. 3B is adevelopment view of the circular cylindrical slope portion of the turnmember.

The damper 10 comprises a resin vessel 20, a slider member 40, a turnmember 60, a viscous fluid V, a partition member 80, a coiled spring120, and a resin cap 100. The resin vessel 20 has a cylindrical chamber21 as illustrated in FIG. 1B. The slider member 40 made of a resin isplaced inside the chamber 21 to divide the chamber 21 into two smallrooms 21 a, 21 b (FIG. 4). The turn member 60 made of a resin is placedin the one room 21 a of the small rooms 21 a, 21 b. The viscous fluid Vis filled in the chamber 21. A partition member 80 made of a resin hasan orifice hole 85 as a communication path for flow of the viscous fluidV between the small rooms 21 a, 21 b. The coiled spring 120 energizesthe slider member 40 toward the turn member 60. The cap 100 made of aresin closes an opening 27 at one end of the vessel 20 and is fixed tothe vessel 20.

The vessel 20 having a cylindrical chamber 21 in the inside thereof hasan opening 22 at another end thereof. The opening 22 is connectedthrough an annular shoulder 23 (FIG. 4) to a cylindrical face 24 (FIG.4) having a larger diameter and further connected through thecylindrical face 24 and a circular shoulder 25 to the inside peripheralface 26 having a larger diameter in the vessel 20. The vessel 20 has alarger opening 27 on the one end opposite to the opening 22 of thevessel 20. On the outside periphery of the opening 27, a flange 28 isformed for fixing the cap 100 to the vessel 20. On the end face of theinside periphery of the opening 27, an annular groove 29 is formed tosurround the opening 27. An O-ring 11 made of a rubber elastomer isfitted into the annular groove 29. In the examples, the vessel 20 isshown to be cylindrical in appearance, but the appearance and the shapeof the vessel 20 is not limited thereto, but may be in a shape of aprismatic column including a triangular prism shape and a quadrangularprism shape.

The slider member 40 has a disk-shaped main body 41 and circularcylindrical slope portion 44 (three slopes in Example) rising at theperimeter of one end face 42 of the main body 41 as illustrated in FIGS.1B, 2A, and 2B. The circular cylindrical slope portion 44 has slopefaces 43 rising from the end face 42 toward the end of the circularcylindrical slope portion 44. The slope face 43 is slanted, in Examplesas illustrated in FIG. 2B, by a slope angle θ1 of 25°. The slider member40 has a cylindrical boss 46 protruding from the center of another endface 45 toward the opening 27. On the outside periphery of the end face45, curved plates 47 (three plates in Example) rise at even intervalsalong the perimeter. The slider member 40 has a round hole 49 extendingfrom circular one end face 46 a of the cylindrical boss 46 throughannular step 48 and a round hole 49 a having increased diameter to theone end face 42.

The body 41 of the slider member 40 has an annular groove 41 b along theperipheral face 41 a. An O-ring made of a rubber elastomer is fitted tothe annular groove 41. The slider member 40 is placed in the cylindricalchamber 21 of the vessel 20 slidably in contact with the insideperipheral face 26 and movable in the chamber 21 to separate the chamber21 into two small rooms 21 a, 21 b.

The turn member 60 has, as illustrated in FIG. 1B and FIGS. 3A and 3B, acylindrical shaft 61, a column 63 having a larger diameter withinterposition of an annular shoulder portion 62 continuous with thecylindrical shaft 61, and a circular cylindrical slope portion 66 havingplural slopes (three slopes in Example) having a larger diameter withinterposition of an annular shoulder portion 64 continuous to the column63. The cylindrical slope portion 66 has a cut slope face 65 having aslope ascending from near the annular shoulder 64 toward the end of thecylindrical slope portion 66, the slope face 65 being slanted at a slopeangle θ2 similar to the slope angle θ1 of the slope face 43 of 25° asillustrated in FIG. 3 b.

The turn member 60 has the shaft 61 inserted into the opening 22 of thevessel 20, and the annular shoulder portion 62 is brought into contactslidably with the annular shoulder 23 of the vessel 20, and annularshoulder 64 is brought into contact slidably with the annular shoulder25 of the vessel 20, and the outside peripheral face of the circularcylindrical slope portion 66 is brought into contact slidably with theinside peripheral face 26 of the vessel 20. Thereby the turn member isplaced in one small room 21 a of the small rooms divided by the slidermember 40. Between the outside peripheral face of the column 63 and theinside peripheral face of the cylindrical face 24 of the vessel 20corresponding thereto, a seal ring 13 made of a rubber elastomer isfitted.

The turn member 60 is engaged with the slider member 40 by contact ofthe cut slope face 65 of the cylindrical slope portion 66 with the slopeface 43 of the cylindrical slope portion 44. The slider member 40 ismoved within the chamber 21 along the inside peripheral face 26 of thevessel 20 with counterclockwise turning of the turn member 60(counterclockwise viewed from the opening 22 in FIG. 1B).

The partition member 80 is constituted of a disk-shaped main body 81,plural legs 83 (three legs in Example) projecting from one end face 82of the main body 81, and engaging-enlarged tips 84 formed on peripheralface of the ends of the legs 83, and a fine orifice hole 85 is formedthrough the center of the main body 81 as a communication path.

For engaging the partition member 80 with the slider member 40, the legs83 are inserted into the round hole 49 opened at the end face 46 a ofcylindrical boss 46 of the slider member 40, and the engaging-enlargedtips 84 of the legs 83 are brought into contact slidably with the insideperipheral face of the round hole 49 a having increased diameter of theround hole 49. Thereby, the partition member 80 is fitted to thecylindrical boss 46 of the slider member 40 to close the opening of theround hole 49. The partition member 80 is thereby fixed by theengaging-enlarged tips 84 to the annular step 48 not to get out of theround hole 49.

A resin-made cap 100, which closes the opening 27 of the vessel 20, hason one end face 101 a cylindrical boss 102 projecting from the one endface 101, and plural curved plates 103 (three plates in Example) risingat even intervals along the perimeter surrounding the cylindrical boss102.

The cap 100 is integrated with the vessel 20 by inserting the curvedplates 103 into the inside peripheral face 26 of the vessel 20 to closethe opening 27 of the vessel 20 and by pressure contact with an O-ring11 placed in a annular groove 29 on the end face of the periphery of theopening 27 of the vessel 20 and by a fixing means like screws 14. Thecurved plates 103 inserted into the inside peripheral face 26 of thevessel 20 has the end portions placed at the interspaces of the threecurved plates 47 of the slider member 40. Thereby the slider member 40and the cap 100 are engaged together at the periphery by the curvedplates 103 and the curved plates 47.

One end 121 of the coiled spring 120 is placed in the space defined bythe outside peripheral face of the cylindrical boss 46 of the slidermember 40 and the inside peripheral face of the cylindrical curvedplates 47 and is brought into contact with the end face 45 of the slidermember 40. Another end 122 of the coiled spring 120 is placed in thespace defined by the cylindrical boss 102 projecting from an end face101 of the cap 100 and the inside peripheral face of the cylindricalcurved plates 103 surrounding the cylindrical boss 102, and is broughtinto contact with the end face 101 of the cap 100. Thereby the coiledspring is held in the vessel 20.

A viscous fluid V is filled as a resisting force generating materialinto the chamber 21 in the vessel 20. A preferred viscous fluid is asilicone oil having a viscosity ranging from 100 to 1000 cst.

The function of the damper 10 is described below with reference to FIGS.4, 5, and 6.

As illustrated in FIG. 4, the turn member 60 and the slider member 40are engaged with each other through the slope faces 55, 43 of thecircular cylindrical slope portions 66, 44. The slider member 40 isenergized by the coiled spring 120 toward the turn member 60. In thisstate, when a counterclockwise external force (turning force) is appliedin a counterclockwise direction to the turn member 60, the slider member40 is driven straightly toward the cap 100 with turning of the turnmember 60 against the energizing force of the coiled spring 120. Whenthe external force applied to the turn member 60 is weaker than apredetermined strength (the turning force being within a range for thepredetermined turning rate), the slider member 40 is moved in thechamber 21, and the viscous fluid V filled in the small room 21 b in thevessel 20 is allowed to flow through the orifice hole 85 of thepartition member 80 into the small room 21 a. As the result, the viscousfluid V produces a throttle resistance at the orifice hole 85 toattenuate the external force applied to the turn member 60. The slidermember 40 can be moved maximally to the position illustrated in FIG. 5

On the other hand, in the state as illustrated in FIG. 4, when anexternal force (turning force) is applied suddenly in thecounterclockwise direction to the turn member 60 at a rate higher than apredetermined range, the slider member 40 is energized to move withinthe chamber 21 against the force of the coiled spring 120. However, theviscous fluid V filled in the small room 21 b produces a large throttleresistance force at the orifice hole 85 of the partition member 80 tocause rigid coupling between the turn member 60 and the slider member40. Owing to this rigid coupling, the turning force applied to the turnmember 60 turns the rigid coupled slider member 40, and turns the cap100 engaged with the curved plates 47 of the slider member 40 at thecurved plates 103 and turns also the vessel 20 fixed to the cap 100.

With the damper 10 in the state illustrated in FIG. 5, when the externalforce applied to the turn member 60 is released, because the slope face43 of the slider member 40 constantly slides engaged with the slope face65 of the turn member 60, the slider member 40 is driven by the springforce (energizing force) of the coiled spring 120 toward the directionin such a manner as that the slope face 43 of the slider member 40 comesinto contact with the slope face 65 of the turn member 60 at a largerarea (as illustrated in FIG. 6). The movement of the slider memberproduces a pressure in the viscous fluid V in the small room 21 a toslide the partition member 80. By this movement of the partition member80, the main body 81 of the partition member 80 closing the opening ofthe round hole 49 is also moved to open the round hole 49. Thereby theviscous fluid V is forced to flow through the opened round hole 49 andthe gap S to the small room 21 b to release the pressure in the smallroom 21 a. Thereby the slider member 40 is driven further toward theturn member 60 and the slope face 43 of the slider member 40 engageswith the slope face 63 of the turn member 60 at a further larger areaand turns the turn member 60 to restore the relative position of theturn member 60 and the slider member 40 (as illustrated in FIG. 4).Incidentally, the engaging-enlarged tips 84 for the engagement formed onthe outside ends of the legs 83 are engaged to the annular step portion48 to keep the partition member 80 not to get out of the round hole 49of he slider member 40.

In the above-mentioned damper 10, the resistance force is generated bythe flow of the viscous fluid V filled in the small room 21 a and thesmall room 21 b through the orifice hole 85 of the partition member 80.In another type of the damper, in place of the orifice hole 85, a groove(not shown in the drawing) is formed at the end face 46 a of thecylindrical boss 46 of the slider member 40 in contact with the end face82 of the main body 81 of the partition member 80 to allow the viscousfluid V to flow through this groove between the small room 21 a and thesmall room 21 b.

An example of the partition member 80 made from an elastomer isdescribed with reference to FIG. 7.

FIG. 7A illustrates a cross-section of a partition member not deformedelastically, and FIG. 7B illustrates a cross-section of the partitionmember deformed elastically.

The partition member 80 mentioned above, which is made of a resin, ishardly deformed elastically by the resistance to the flow of the viscousfluid V through the orifice hole 85. On the other hand, the partitionmember 180 in FIGS. 7A and 7B is made of an elastomer (e.g., rubber),and is readily deformable by the aforementioned flow resistance. Thepartition member 180 made of an elastomer is kept undeformed asillustrated in FIG. 7A when the resistance force is not produced by theflow of the viscous fluid V through the orifice hole 85. The diameter ofthe orifice hole 85 in this undeformed state is defined to be L1.However, when a resistance force is produced to retard the flow of theviscous fluid V at the orifice hole 85, the partition member 180 isdeformed elastically corresponding to the resistance force asillustrated in FIG. 7B. FIG. 7B illustrates a state in which the viscousfluid V flows from the small room 21 b into the small room 21 a(transition of the state from FIG. 4 to FIG. 5). In this state theminimum diameter of the orifice hole 85 is L2 (L1>L2). The greater theresistance, the smaller is L2. That is, the greater the resistance (thehigher the velocity of the external force acting on the turn member 60),the smaller is the minimum of the diameter L2 to retard the turn of theturn member 60, whereby a damper of load-sensitive type is obtained.

Next, a vehicle seat incorporating the above damper 10 is described withreference to FIGS. 8 and 9.

FIG. 8 is a schematic side view of a vehicle seat 200 incorporating adamper 10. FIG. 9 is a schematic front view of the vehicle seat 200illustrated in FIG. 8.

The vehicle seat 200 contains seat cushion 202 for sitting of a ridingperson, a backrest 204 to be in contact with the back of the ridingperson, and a headrest 206 for protecting the head of the riding person.The backrest 204 contains inside an energizing mechanism 210 forenergizing the headrest 206 to move forward; a stopping mechanism 220for stopping the energization by the energizing mechanism 210 not tocause the forward movement of the headrest 206; and a releasingmechanism 230 for releasing the stopping action of the stoppingmechanism 220 to actuate the energizing mechanism 210. The backrest 204contains further, in the lower part thereof, the aforementioned damper10, and an external force receiving pad 240 which allows the turn member60 of the damper 10 to turn by receiving an external force.

The energizing mechanism 210 has a center shaft 212 extending in thevehicle width direction and an energizing plate 214 extending in thevehicle height direction at the upper portion of the backrest 204. Theenergizing plate 214 is fixed at the top end to the headrest 206, and isfixed to be turnable at the middle in the vehicle height direction tothe center shaft 212. At the lower portion than the center shaft 212 ofthe energizing plate 214, an end of a coiled spring 216 is hooked whichenergizes to turn the energizing plate 214 around the center shaft 212in the arrow P direction. Another end of the coiled spring 216 is fixedto the rear side of the backrest 204. At the upper portion than thecenter shaft 212 of the energizing plate 214, a stopper 218 is placed toprevent turn of the energizing plate 214 in the direction reverse to thearrow P beyond the position indicated in FIG. 8. Thus the headrest 206is constantly energized by the energizing mechanism 210 to move towardthe front of the vehicle (to move to the position indicated by thebroken line in FIG. 8). However, without impact to the vehicle, theenergization by the energizing mechanism 210 is stopped by the stoppingmechanism 220.

The stopping mechanism 220 has a stopping plate 224 having a projection222 for hooking the bottom end of the energizing plate 214, and a coiledspring 226 for energizing the stopping plate 224 toward the arrow Qdirection. The stopping plate 224 spreads nearly parallel to the seatcushion 202 and the coiled spring 226 is placed higher than the stoppingplate 224. The stopping plate 224 has the projection 222 at the rear endportion, and is fixed to be turnable around the center shaft 228extending in the vehicle width direction. Near a rear end portion of thestopping plate 224, one end of the coiled spring 226 is fixed. Near thecoiled spring 226, a stopper 227 is placed not to cause turn of thestopping plate 224 in the arrow Q direction beyond the positionillustrated in FIG. 8.

The releasing mechanism 230 has a wire 232 which is connected to the cap100 of the damper 10 and is moved with the movement of the cap 100.

An external force receiving pad 240 receives an external force towardthe rear of the vehicle caused by the collision from the rear side ofthe vehicle or the like. The external force receiving pad 240 is fixedto the turning shaft 242. The turn member 60 of the damper 10 isconnected and fixed to the turning shaft 242, and the vessel 20 issupported to be turnable by a fixed axis (not shown in the drawing) atthe boss 72 of the cap 70. When an external force toward the rear sideof the vehicle is applied to the backrest 204, the external forcereceiving pad 240 turns around the turning shaft 242 and turns towardthe rear side of the vehicle (in the counterclockwise direction)together with the turning shaft 242.

In the case where the load is applied to the backrest 204 at a loadingrate within a predetermined turning speed range by seating of a personon the seat cushion 202 of the vehicle seat 200, for example, in thecase where ordinary loading toward the rear side of the vehicle by theriding person, or additional loading toward the rear side of the vehicleby the riding person on acceleration of the vehicle, the load is slowlyapplied to the backrest 204. As the result, the external force receivingpad 204 which has received the load of the riding person turns slowlyaround the turning shaft 242 which has the external receiving pad 240fixed thereto. The force of the slow turning of the turning shaft 242 istransmitted to the turn member 60 of the damper 10 connected to theturning shaft 242 to turn the turn member 60 in the counterclockwisedirection. With the turn of the turn member 60, the slider member 40which engages therewith through the slope face 65, 43 of the cylindricalslope portions 66, 44 is moved in the chamber 21 of the vessel 20against the energizing force of the coiled spring 120.

Since the slider member 40 moves slowly in the chamber 21 of the vessel20, the viscous fluid V filled in the small room 21 b of the vessel 20flows through the orifice hole 85 of the partition member 80 into thesmall room 21 a with little flow resistance of the viscous fluid V.Therefore, the cap 100 which is engaged with the slider member 40through the curved plates 47 and the curved plates 103 in the peripherywill not be turned, and the vessel 20 fixing the cap 100 will not beturned also. Thus, a pulling force which causes the turn of the stoppingplate 224 to release the contact and engage with the end of theenergizing plate 214 is not caused in the wire 232 connected to the cap100, so that the turn of the headrest 206 forward in the P direction isstopped to keep the headrest in the normal position.

On the other hand, when a great acceleration affects the person sittingon the seat cushion 202 by rear end collision, the external forcereceiving pad 240 is turned instantaneously around the turning shaft 242supporting the external force receiving pad 240, and the turn member 60of the damper 10 fixed to the turning shaft 242 is turnedinstantaneously in the counterclockwise direction. This turn of the turnmember 60 tends to move the slider member 40 in the chamber 21 of thevessel 20 against the energizing by the coiled spring 120. However, theviscous fluid V filled in the small room 21 b produces strong throttleresistance at the orifice hole 85 of the partition member 80 to connectthe turn member 60 with the slider member 40 by rigid coupling. In thisstate, the turning force given to the turn member 60 turns the slidermember 40 rigid-coupled to the turn member 60 together with the cap 100engaged at the perimeter with the curved plates 47 of the slider member40 through the curved plates 103.

The turn of the cap 100 pulls downward the wire 232 connected to the cap100, and turns the stopping plate 224 connected to the wire 232 aroundthe shaft 228 in the direction reverse to the arrow Q. This turndisengages the projection 222 hooking the lower end of the energizingplate 214 from the energizing plate 214 to allow the energizing plate214 to turn in the arrow P direction by the energizing force of thecoiled spring 216. Thereby the headrest 206 is turned in the arrow Pdirection to hold the head of the riding person (turned to the positionindicated by a broken line).

In the above-mentioned vehicle seat 200, the head rest 206, after theturn forward in the P direction, can be restored to engage with thestopping plate 224 at the end of the energizing plate 214 by forcing theheadrest 206 to turn the direction reverse to the P direction to engagethe end of the energizing plate 214 with the projection 222 of thestopping plate 224.

The recovery of the hooking of the energizing plate 214 by the stoppingplate 224 allows the turn of the cap 100 connected to the wire 232 andpulled by the wire 232 connected to the stopping plate 224, and theslider member 40 engaged at the periphery with the curved plates 103 ofthe cap 100 through the curved plates 47 is displaced by energization bycoil spring 120 and turn the turn member 60 engaged with the slidermember 40 to restore the slider member 40 and the turn member 60 to theoriginal positions (in the state illustrated in FIG. 4).

1. A damper for damping an external force, comprising: a vessel having acylindrical chamber therein; a slider member placed in the chamber anddividing the chamber into two small rooms and movable in the cylindricalchamber; a turn member placed in one of the two small rooms, turned bythe external force, and converting the turning force into a drivingforce of the slider member; a viscous fluid filled in the chamber; apartition member engaged with the slider member and having acommunication path for flow of the viscous fluid between the two smallrooms; a coiled spring for energizing the slider member toward the turnmember; and a cap fixed to the vessel by engaging with the slider memberand blocking an opening at one end of the vessel.
 2. The damperaccording to claim 1, wherein the partition member has an orifice as thecommunication path.
 3. The damper according to claim 1, wherein theslider member has a cylindrical boss having at the end face thereof agroove serving as the communication path.
 4. The damper according toclaim 1, wherein the turn member has a circular cylindrical slopeportion having slope faces, the slider member has a circular cylindricalslope portion having slope faces for engaging with the slope faces ofthe turn member, and the slider member is allowed to move in thecylindrical chamber by turning the turn member engaging the slope facesof the turn member with the slope faces of the slider member.
 5. Thedamper according to claim 1, wherein the slider member has plural curvedplates rising along the perimeter at even intervals on the faceconfronting the cap; the cap has plural curved plates rising along theperimeter at even intervals on one face thereof; and the curved platesof the slider member is inserted into the intervals of the curved platesof the cap to engage the slider member with the cap at the peripherydirection.
 6. (canceled)
 7. (canceled)
 8. The damper according to claim2, wherein the turn member has a circular cylindrical slope portionhaving slope faces, the slider member has a circular cylindrical slopeportion having slope faces for engaging with the slope faces of the turnmember, and the slider member is allowed to move in the cylindricalchamber by turning the turn member engaging the slope faces of the turnmember with the slope faces of the slider member.
 9. The damperaccording to claim 2, wherein the slider member has plural curved platesrising along the perimeter at even intervals on the face confronting thecap; the cap has plural curved plates rising along the perimeter at evenintervals on one face thereof; and the curved plates of the slidermember is inserted into the intervals of the curved plates of the cap toengage the slider member with the cap at the periphery direction. 10.The damper according to claim 3, wherein the turn member has a circularcylindrical slope portion having slope faces, the slider member has acircular cylindrical slope portion having slope faces for engaging withthe slope faces of the turn member, and the slider member is allowed tomove in the cylindrical chamber by turning the turn member engaging theslope faces of the turn member with the slope faces of the slidermember.
 11. The damper according to claim 3, wherein the slider memberhas plural curved plates rising along the perimeter at even intervals onthe face confronting the cap; the cap has plural curved plates risingalong the perimeter at even intervals on one face thereof; and thecurved plates of the slider member is inserted into the intervals of thecurved plates of the cap to engage the slider member with the cap at theperiphery direction.
 12. The damper according to claim 4, wherein theslider member has plural curved plates rising along the perimeter ateven intervals on the face confronting the cap; the cap has pluralcurved plates rising along the perimeter at even intervals on one facethereof; and the curved plates of the slider member is inserted into theintervals of the curved plates of the cap to engage the slider memberwith the cap at the periphery direction.
 13. The damper according toclaim 8, wherein the slider member has plural curved plates rising alongthe perimeter at even intervals on the face confronting the cap; the caphas plural curved plates rising along the perimeter at even intervals onone face thereof; and the curved plates of the slider member is insertedinto the intervals of the curved plates of the cap to engage the slidermember with the cap at the periphery direction.
 14. The damper accordingto claim 10, wherein the slider member has plural curved plates risingalong the perimeter at even intervals on the face confronting the cap;the cap has plural curved plates rising along the perimeter at evenintervals on one face thereof; and the curved plates of the slidermember is inserted into the intervals of the curved plates of the cap toengage the slider member with the cap at the periphery direction.